Process and apparatus for polishing glass



Dec. 15, 1953 E. J. G. LAVERDISSE PROCESS AND APPARATUS FOR POLISHING GLASS '7 Sheets-Sheet 1 Filed March 23, 1949 Dec. 15, 1953 E. J. G. LAVERDISSE A PROCESS AND APPARATUS FOR POLISHING GLASS Filed March 23, 1949 7 Sheets-Sheet 2 v v I E. J. G. LAVERDISSE PROCESS AND APPARATUS FOR POLISHING GLASS Filed March 23. 1949 Dec. 15, 1953 7 Sheets-Sheet 3 I/vvE/vTo/t Ezmwvb J6. laymen/S E ll s/yrs D m 1953 E. J. G. LAVE'RDISSE PROCESS AND APPARATUS FOR POLISHING GLASS Filed March. 23. 1949 7 Sheets-Sheet D c- 5, 1953 E. .1. e. LAVERDISSE 2,662,350

PROCESS AND APPARATUS FOR POLISHING GLASS Filed March 25 j 7 Sheets-Sheet 5 Dec. 15, 1953 Filed March 23,

E. J. G. LAVERDISSE PROCESS AND APPARATUS FOR POLISHING GLASS 1949 7 Sheets-Sheet e Dec. 15, 1953 E. J. G. LAVERDISSE PROCESS AND APPARATUS FOR POLISHING GLASS Filed March 25, 1949 7 Sheets-Sheet '7 Patented Dec. 15, 1953 PROCESS AND APPARATUS FOR PGLESHING GLASS Edmond Joseph Ghislain Laverdisse, Auvelais, Belgium, assignor to Les Glaceries de la Sambre Societe Anonyme, Auvelais, Belgium, a Belgian company Application March 23, 1949, Serial No. 83,0143

Claims priority, application Belgium March 27, 19%

14 Claims.

The present invention relates to a process of polishing glass and a machine for carrying out this process.

it is known, for the production of polished glass, to lead an endless band or sheet of glass coming from the furnace through a lehr where it is subjected to slow and methodical cooling, whereupon it is subjected to grinding by discs of cast iron under which rough sand is fed in order to wear down asperities in the glass and to determine the planimetry and the parallelism of its faces, the glass then being subjected to polishing which confers thereto its transparence and shine.

The polishing operation is performed by means of felt discs called polishers, which are impregnated with a paste of iron oxide herein referred to as the polishing composition, and are rotated and pressed against the glass with increasing pressure. It is known to submit simultaneously both faces of the glass to grinding, then to polishing, and in either case, to select the direction of rotation of the tools so that their reactions on the glass are opposed, thereby reducing stresses in the glass. While this system has generally proved to be satisfactory for grinding, the frictional pressure of the tools on the glass being low, it has inconveniences in polishing, where the coefficient of friction increases materially as the surface of the glass becomes heated,

whereby transverse stresses take place in the V glass, its progression is impeded and breakage may occur. Moreover, it is necessary to leave, between successive polishers, relatively large spaces to allow cooling of the glass, but this prolongs the duration of the operation.

It is the object of present invention to avoid these inconveniences and, in accordance therewith, there are imparted to the polishing tools rectilinear reciprocating movements transversely i the forward progression of the glass These reciprocating movements of the tools take place in opposite directions of the tools working opposite each other on both sides of the glass, and/or for the tools working in succession on the same side of the glass. Thus dangerous stres es in the glass are avoided.

Another advantage of this process consists in making it possible to locate closer to each other the tools working in succession on the glass and consequently to reduce the causes for cooling the glass. This advantage is particularly noticeable when, according to one embodiment of this invention, the polishers have a square or rectangular shape instead of the usual circular shape.

Whatever be the shape of the polishers, these may be rotated While they perform their reciprocating motion transversely of the direction of progress of the glass. Moreover, they may advantageously be moved in the direction of progression of the glass, in order to diminish their resistance to said progression, the movement of the polishers being either at the same speed as, at a lower speed or at a higher speed than the prog ession of the glass. I

In order to carry out these various motions, the polishers are mounted on beams arranged in pairs, one below and the other above the glass, transversely thereof.

The lower beam is mounted on a frame which carries the mechanism for reciprocating same and the means for feeding same with polishing composition and with oil. The upper beam is also mounted on said frame, which may be stationary or movable. In the latter case, the frames move in the same direction as the glass and when the polishing operation is completed, the two beams of each pair are successively separated, brought back to their initial position and again set in action while they again start their movement on the glass.

An embodiment of the machine according to this invention is illustrated diagrammatically by way of example in the accompanying drawings.

Fig. 1 shows in longitudinal elevation and part section a general view of the machine.

Fig. 2 is on a larger scale a cross section on line II-II of Fig. 1.

Fig. 3 is a fragmentary plan view of the machine.

Fig. i is a fragmentary plan view showing a modification.

Fig. 5 is on a larger scale, a fragmentary s ction on line V-V of Fig. 2.

Fig. 6 is a cross section on line VI-VI of Fig. 2.

Fig. 7 is a plan view of the lower downward lift.

Fig. 8 is an elevation on a larger scale of the upper upward and downward lifts.

Fig. 9 is a fragmentary section on line Iii-IX of Fig. 1.

Fig. 10 is a corresponding plan view.

Fig. 11 is a plan view of the actuating mechanism for the upper downward lift.

Figs. 12 and 13 are schematic wiring diagrams of the machine.

The machine illustrated in Figs. 1 to 3 is adapted to receive a continuous glass band or sheet 5 which has already been subjected to grinding and may or may not have been subjected to preliminary polishing, said glass sheet being fed on rolls 2. The sheet i thus passes between the lower polishers 3 carried by beams i and the upper polishers carried by beams 6 the polishers 3 and E are respectively rotated by means of worms 93, 95 actuated by motors 92, 84 carried by the beams e, E3. The polishers 3 and 5 being brought into contact with both sides of the glass respectively, the beams 3 and 6 are reciprocated, preferably in opposite directions as will be described hereafter. While polishing thus takes place, the beams are carried in the same direction as the glass sheet so as to accompany same to the exit end of the machine. Before the end, the polishers are moved away from the glass and, in the example considered, their forward movement is accelerated so that, without the work being interrupted, each lower beam 4 is brought down by a downward lift 1 on a lower set of rolls 8, while the corresponding upper beam 6 is lifted by an upward lift 9 and deposited onto an upper set of rolls is. The beams 4 and t are then brought back to the entrance end of the machine, where an upward lift 5 i and a downward lift I2 respectively bring them back into their initial positions in order to start again the polishing operation.

Fig. 2 illustrates a pair of beams in operative position. The beams c and 3 are mounted for reciprocating movement across the glass in a frame made of two parts 13, Hi, which frame is slidably mounted on a base comprising a pair of rails i5 parallel to the glass sheet 1 To this end each part it, M is provided with a rack section i6 adapted to be engaged in turn by a driving wheel 11.

The transverse movements of the beams are imparted thereto by connecting rods [8, l9 driven by crank discs 29, 2! rotated by a motor 22 through a speed reducing gear 23, all these parts being carried by the frame 14. The movements of the two beams are synchronised by a chain 24, the crank pins 25, 25 being preferably at 180 from each other so that the beams always move in opposite directions, one being at the end of its leftward stroke when the other is at the end of its rightward stroke. Thus transverse stresses in the glass sheet are reduced to a minimum.

The polishers 3 and 5 are advantageously of rectangular shape as shown in Fig. 3, this shape insuring a great working efficiency when the polishers are mounted. against rotation in their carrying beams. They may however have another shape, such as a circular shape, and be mounted for rotation as shown in Fig. 4. In order still further to reduce the stresses in the glass, it is advantageous to alternate the movement of adjacent beams, one beam moving from right to left, while the preceding one and the following one move from left to right.

In the example illustrated in Fig. 2, the part I3 of the frame carries a receptacle 2'! for the polishing composition which, by means of the pump 28 supplies the polishers 3 and 5 through pipes 29, 3d. When, as shown in Fig. 3, the polishers do not rotate, the composition may be poured near their edges (as shown at 3!, in Fig. 5), whereby a better distribution of the composition over the whole surface of the polishers is obtained.

In proximity to the receptacle 21 is an oil receptacle 32 which, by means of pump 33 and pipes 36, 35, feeds the cylinders 36 (Fig. 5) with oil adapted to press the polishers against the glass, under the action of pistons 31 and against the pressure of return springs 38. Instead of hydraulic pistons,

other means such as adjustable springs may be used for controlling the pressure of the polishers.

The frames l3, I i also carry brackets 39 (Fig. 6) with freely rotating rolls 40 adapted to support the glass between the successive rolls of polishers 3.

As shown in Fig. l, the successive beam-carrying frames are in contact with each other, each frame pushing the preceding frame along the rails I5, under the action of the gears H driven from motors not shown. Thus the beams travel in the same direction as the glass while polishing same. The speed of travel of the beams need not be equal to that of the glass sheet, but it may be greater or smaller than the speed of the glass.

It is also seen that this arrangement reduces to a minimum the portion of the glass sheet or band which, at a given moment, is located between two sets of polishers and is exposed to cooling. Thus the high temperature of the glass surface, which is favorable to polishing, is better preserved than with the known devices.

The frames l3, #4 are provided with contact pieces 18 (Fig. 2) which engage bus-bars 79 extending from the entrance to nearly the exit end of the machine in order to supply current to the motors controlling the reciprocating movements of the beams, the supply of composition, oil, etc.

When polishing is finished, the beams are near the exit end of the machine. At this point the bars 19 are interrupted and they are extended by short bar sections 19' to which they are connected by connections 8! under the control of a contactor 82 mounted on a stationary support 83 (Figs. 9 and 10).

In order that, on leaving the machine, the uper beams 5 will occupy the required position to be caught by the upward lift 9, the contactor 82 is controlled by a switch 4, situated in the path of an abutment 85 secured to the beam 4. During the reciprocating movement of the beam under the action of motor 22, the abutment 85 opens the switch 84, thus interrupting the supply of current to the bars 19' and causing the motor 22 to stop, whereby the beams are stopped in a central position. The motors actuating pumps 28 and 33 are stopped at the same time and the polishers are returned back to their inoperative positions under the action of the springs 33. The abutment 85 so proportioned as to break the supply of current to the bars 19' until the corresponding beam is disengaged therefrom, whereupon the switch 84 is returned back to its closed position by a spring 86.

The frame !3, M is then engaged by a dog 4! (Fig. 1) on a fast moving chain 42 which carries the frame towards and onto the downward lift 2 which is provided with a rack driven by gears '56 from the motor T! (Fig. 7). At the same time hooks 43 on the upward lift 9 engage, as herein- Mter described, a suspension bar 44 on the beam 6 and lift the same from the frame i3, M. Meanwhile an operator has disconnected couplings c5, 46 inserted in the composition pipe 30 and oil pipe 35 which are also provided with non return valves 41, 48.

When the frame I3, [4 carrying the beam 4 is in position on the downward lift 1, it has engaged the contact 8'! and caused same to energize motor 11. The lift 1 lowers the frame l3, l4 down to the level of the lower set of rolls 8 on which it is pushed by a dog 49 on a chain 50, at the same time actuating the switch 88 which reverses the rotation of motor 11 and causes the lift 1 to move upwards in order to fetch the next frame !3, l4. As it reaches the entrance of the machine, the frame it, it moves the switch 89 controlling the upward lift H and is carried up by the latter until it is again under the level of the glass sheet. At this moment the upper beam 6 coming from the upper set of rolls it is brought by the downward lift l2 onto the frame 53, it, where it is centered by the conical points 5i which fit exactly into corresponding recesses provided on the beam t.

The frame it, i i is then pushed by a dog 52 on a chain 53, operating on its way the switch til, causing the lift 5 i to move downward. released by the dog 52, the frame it, it just raised by the lift 3! is pushed against the preceding frames it, it on the rails it by the arm 5%, pressed by spring 55. A. cam 56 is provided for periodically pushing said arm back. From that moment the rack it of he frame in question is again engaged by the gear ii, the contact pieces it again engage the bars E3, the polishers are again brought into contact with the glass and start their operation.

The construction of the upper lifts, i. e. the upward lift 8 the downward lift i2 is shown detail on Figs. 8 and 11. These apparatus are arranged symmetrically at both ends of the machine and they comprise rocker arms El carrying a cross bar 553 on which are suspended the hooks 43 for successively engaging and releasing the suspension bars i i of the beams t.

The arms Eil which are mounted on each side of the machine, are pivoted on trunnions 59 in stationary bearings til (Fig. 11). Rigidly connected with said arms are toothed sectors 6i meshing with sectors 62 which through shaft 53, rs fit and a reducer 55, are driven from reversible motor mounted on a platform 89.

In Fig. 3, the ants El of lift 9 as illustrated in .iuil line, are in waiting position, i. e. in read;- iness for engaging an incoming beam. In the ends of the arms 5'? is pivoted at 6? the cross bar which normally urged by the Weight 58 to take up a position in which the hooks d3 are ready to engage the suspension bar d4 of the first incoming beam.

he beam (3 whose bar is engaged by the hooks it carries a finger which closes a switch ill for starting the motor The arms 5'! then are lifted with the beam 6, the cross bar 58 pivctin on the axis or during this movement, until the 5 rests on the set of rolls ill. At that moment, the finger "ii on the cross bar has closed the reversing switch T2 for the motor 65 and the cross 58 compressed a spring '13 which, as soon as the arms 5? start on their return stroke, quickly tips the cross bar 53 so that the bar of the beam 3 is freed by the hooks 43.

While the beam t is carried by dogs it on the rolls it towards the entrance end of the machine, the arms 5? or the lift 9 are moved downwards and the beam lit again takes up its waiting position, as it pushes the switch l5 which causes the stoppage and reversal of the motor 35.

The same movements take place in the downlift 52 which takes the beam 5 from the rolls it and lowers it until it is at the level of the glass and comes to rest on the frame l3, l4 brought up by the lower lift l I.

It will be understood that the frame 13, i l carrying the lower beam d, closes the switch 87 when it positioned on lift '3. Electric current then energizes coil lilo (see Fig. 12), closes contactor lill, the contacts N3 of which connect the current supply terminals with the leads to motor Ti. This motor is set into motion and lowers the lift 1 with the beam 6 until the carrying frame l3, Hi has reached the level of the lower rolls 8. At the same time, through pinions M5, M35, said motor rotates the disc Hi l which, at the lower end of the travel of the lift l brings the end it? of the contacting strip tilt between two adjustable points Ills, lit. The circuit thus is closed, coil Hill being ole-energized, disconnects the supply at its, stopping the motor ii.

The frame it, it is then, as explained before, pushed on the rollers 8 by a finger 4Q (Fig. 1)

by chain 0n its Way, the frame actuates the switch 88, which starts the motor ii in reverse direction to move the lift '5 upwards. It will be understood that the switch 28 being closed, coil H i or" contactor I 52 will be energized and close the contact H3, thereby causing current to be supplied to terminals l 523 and rotate the motor l! in the reverse direction.

The switches 8?, 8% are closed only for a very short time. Contactors it! and H2 are caused to remain in the energized position by the moving contacts H 3 and H5 or the respective lockdevices lid, ill, as long the points I05, lid on the one hand, the points H8, M9 on the other hand are interconnected.

At the inlet end of the machine, a motor T3 for the lower lift operates in the same manner, so that when the frame 53, i l carrying the beam 4 closes the switch the lift i! is raised and stopped when the lower tools 3 have reached the level of the under surface of the glass. The operation is just the same as has been described with respect to lift '1.

As the lower beam is again in working position, its points 5i engage in the corresponding recesses of the upper beam 6 which meanwhile, has been lowered by the upper lift l2.

The frame iii-4d, is then engaged as described in Fig. l by a finger 51 carried by the chain 53, and it actuates on its way the switch fill in order to cause the lift H to move downwards. The frame i3, it is pushed against the preceding frame by the arms at as previously described. From that moment, the rack it is engaged by the gear ii, the contact pieces it engage the feed bars 18 and the polishing tools start again to work.

Refer 'ing to Fig. 8, the arms 5? of the lifts d are illustrated in full lines, in the waiting position. The cross bar 58 pivotally mounted at Sl on the ends of the arms 5'2, is by a weight 63 in a position adapted to allow the suspension bar iii of the first oncoming beam. '5 to be engaged by the hooks 5-3.

When the said beam is seized by the hooks :33, it closes by means of finger the switch lil which starts the operation of motor 56 as will be explained with reference to Fig. 13. From switch it current passes through energ-izes coil itd of cont-actor till, the movable con tacts 522 of which connect the current supply terminals 23 with the terminals E24 of "motor Motor 66 is set in operation, and rocks upwardly the arms 5? which lift the beam 5; meanwhile the weight of the beam 6 causes the cross bar to pivot on the axis El so that the beam it remains in the vertical position until it is deposited by the arms ii on the upper rollers 58.

During this time, motor 65 has rotated disc E25 which is fitted with a contact st. p similar to strip its described in connection with motor iii, the rotation of the motor being stopped at the moment the spring '53 compressed by the cross bar 58, causes the latter to tilt backwards and. the hooks &3 to free the suspension bar 44. This tilting movement causes finger H (Fig. 8) to close contact 32, which, as shown in Fig. 13 reverses the rotation of motor 85, thereby causing the arms 52 to move back to the position illustrated in full lines in Fig. 8. The downward movement of said arms is stopped by the breakin of the contact between the strip on disc I25 and the contact points, in the same manner as has been explained with respect to strip I08 and contact points Hi9, HE, and H8, H9.

It will be understood that the reverse rotation of motor 36 has been obtained by the energization of coil E26 closing the contacts I28 which connect the supply of current with the terminals E36 of motor 63.

The operation of lift it is controlled by a motor in exactly the same manner as has been described for lift 9, controlled by motor 66.

In a like manner to that described in connection with the operation of motor ll, the switches 73 and T2, are closed only for a very short time, and the contacts i222 and E28 are controlled by suitable locking devices, as explained in connection with reference to Fig. 12.

It is obvious that constructional modifications may be effected in the machine as described and illustrated, without departing from the scope of the appended claims. When the beams are mounted on stationary frames, the mechanisms for moving the beams along with the glass band, for moving them away from the band and then back to their positions are of course omitted, and the glass may be stationary or kept in motion during the polishin operation.

It will further be understood that instead of a rectilinear reciprocating movement, the beams may have imparted thereto a curvilinear motion or they may be moved in a closed path across the glass band. In each of these cases, care will be taken to move the upper and lower beams, and/or adjacent beams in opposite directions in order to reduce transverse stresses in the glass.

I claim:

1. A process of simultaneously polishing both sides of a sheet of glass, comprising feeding a glass sheet between sets of upper polishing tools and sets of lower polishing tools supported to rotate on vertical axes, applying adjustable pressure to said tools towards said glass sheet rotating said sets of tools on their vertical axes, imparting to said sets of tools rectilinear reciprocating movements transversely of said sheet; the r polishing tools operating on one side of the glass being moved in opposite direction to the polishing tools operating on the other side of the glass. 2. A process of simultaneously polishing both sides of a sheet of glass, comprising continuously feeding a glass sheet between two sets of polishing tools supported to rotate on vertical axes, adjustably pressing the tools of one set against one of said sheet and the tools of the other set against the other side of said sheet, and simultaneously imparting to both sets of tools rectilinear reciprocating movements transversely of said sheet, adjacent tools of each set being rotated in opposite directions relatively to each other, the polishing tools on one side of the glass being moved in opposite direction to the polishing tools of the other side of the glass.

A process of simultaneously polishing both of a sheet of glass comprising feeding a sheet in a substantially horizontal direction between two sets of polishing tools, adjustably pressing the tools of one set against one side of said sheet and the tools of the other set on the other side of said sheet, imparting to both sets of tools rectilinear reciprocating movements transversely of said sheet in mutually opposite directions, and. imparting to each tool a rotation about an axis at right angles to the glass sheet.

4. A process of simultaneously polishing both sides of a sheet of glass, comprising feeding a glass sheet in a substantially horizontal direction between two sets of polishing tools, adjustably pressing the tools of one set against one side of said sheet and the tools of the other set on the other side of said sheet, imparting to both sets of tools rectilinear reciprocating movements transversely of said sheet in mutually opposite directions, imparting to each tool a rotation about an axis at right angles to the glass sheet, and impartingto both sets of tools a movement in a direction parallel to the direction of feed of the glass sheet, but at a speed different from the speed of said sheet.

5. A machine for simultaneously polishing both sides of a sheet of glass, comprising a base, frames on said base, means on said frames for supporting a glass sheet in substantially horizontal position, pairs of beams on said frames comprising each an upper beam and a lower beam, said beams being supported on said frames for facing opposite sides of the glass sheet, polishing tools on each of said beams, supported to rotate on axes extended at right angles to said beams the tools on said upper and lower beams having flat surfaces adapted respectively to polish the lower side and the upper side of said glass sheet, means connected to said tools for rotating said tools on their rotation axes, means on said frames for imparting to said beams rectilinear reciprocating movements across the glass sheet in opposite directions to each other.

6. A machine for simultaneously polishing both sides of a sheet of glass, comprising a base, frames on said base, means on said frames for supporting a glass sheet in substantially horizontal position, pairs of beams on said frames each comprising an upper beam and a lower beam, polishing plates mounted on vertical axes in each of said beams, the plates on said upper and lower beams being adapted respectively to polish the lower side and the upper side of said glass sheet, means on each frame for rotating said plates about their respective vertical axes, means on said beams for applying pressure to said plates, means on said frames for feeding polishing composition to the polishing plates on the pair of beams carried by said frame, means on said frames for imparting to said beams rectilinear reciprocating movements across the glass sheet and means on one of said frames interconnecting the beams of each pair to cause the beams of each pair to move in oppo site directions to each other.

'7. A machine for simultaneously polishing both sides of a sheet of glass, comprising a base, frames movably positioned on said base, movement toward one end thereof, means on said frames for supporting a glass sheet in substantially horizontal position, a lower beam movably supported on said frames for facing the lower side of the sheet of glass, an upper beam movably supported on said frames above said lower beam for facing the upper side of the sheet of glass, sets of rotary polishing plates supported on each of said beams to rotate on axes extended at right angles to said beams, the plates on the upper beam and on the lower beam being adapted to polish the upper and the under side of said glass sheet respectively, means on one of said frames for reciprocating said beams in opposite di ections across said glass sheet, a receiving structure extending above said frames, and means on said structure adjacent the said one end of said frame for lifting said upper beam from said frame onto said structure.

8. A machine for simultaneously polishing both sides of a sheet of glass comprising a pair of elongated parallelly spaced rails frames rested on said rails to be movable parallel to the length of said rails, means on said frames for supporting a glass sheet along a substantially horizontal plane; pairs of beams on said frames comprising each a beam above and a beam below said plane, sets of polishing tools on each of said beams supported to rotate on axes extended at right angles to said plane, means connected to said sets of tools for rotating said sets of tools, the upper beams of each pair being removably supported on its carrying frame, means on said frames for imparting to said beams reciprocating movement transversely of the glass sheet, and means for moving said frames on said rails.

9. In a machine according to claim 8, a structure extending above said rails, said moving means moving said frames toward one end of i said rails; means on said structure adjacent the said one end for successively lifting each upper beam from its carrying frame at the said one end of the machine and placing it on said structure, and means on said structure for separately returning the successive upper beams to the other end of the machine.

10. In a machine according to claim 8, wherein the moving means moves the frames toward one end of the rails, means at the said one end of the machine for successively lifting each upper beam from its carrying frame, means at the said one end of the machine for successively lowering each carrying frame with its lower beam structures above and below the rails to receive and move the raised upper beams and the lowered frames to the other end of the rails, means at the said other end of the rails for separately returning the successive upper beams and the successive carrying frames with their lower beams to the rails at the other end thereof, and means at the other end of the machine for bringing each successive upper beam together with its carrying frame.

11. In a machine according to claim 10, means carrying frame and means at the said other end 0 of the machine for separately returning the up- 19 per beams and their carrying frames to their operative positions.

12. In a machine according to claim 8, an upward lift and a downward lift for the successive upper beams at the exit end and at the entrance end of the machine respectively, means operated by said upper beams for controlling the movements of both said lifts, a downward lift and an upward lift for the successive carrying frames at the. exit end and at the entrance end of the machine respectively, and means operated by said frames for controlling the movement of both last mentioned lifts.

13. In a machine according to claim 8, a structure extending above said frames, an upward lift and a downward lift for the successive upper beams at the exit end of the machine and at the entrance end of the machine respectively, each said lift comprising a pair of rocker arms pivotally mounted on said structure, a tiltable cross bar journalled in said arms, hooks on said cross bar for engaging each successive upper beams and means operated by said upper beams for controlling the movements of said lifts.

14. In a, machine according to claim 8, a structure extending above said frames, an upward lift on said structure for successively lifting each upper beam from its carrying frame at the exit end of the machine, and stop means positioned on said machine adjacent the exit end of the machine to be engaged by said upper beams as they approach the exit end for stopping each upper beam in a predetermined position before it reaches the exit end of the machine.

EDMOND JOSEPH GHISLAIN LAVERDISSE.

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